Physical medium information in file system header

ABSTRACT

Data storage units, such as flash memory, nonvolatile random access memory and like, are provided with information stored therein, or physically coupled thereto, which indicates, or can be used to determine, remaining or impending end of lifetime of the data storage unit or its components. In a flash memory embodiment, a counter initialized to the number of maximum permissible flash memory erasures is stored in a counter, such as in the header portion of the flash memory. The counter is decremented with each erasure and, as the counter approaches zero, appropriate actions can be taken such as warning the user, support personnel, vendor and the like and/or disabling the flash memory.

FIELD OF THE INVENTION

The present invention relates to the storage of information relating toa physical data storage medium indicative of its usage or designlifetime such that at least some of the information remains coupled tothe medium such as storing, in a flash memory header, informationrelating to the number of flash memory erasures.

BACKGROUND OF THE INVENTION

A number of information storage media have a predeterminable orcalculable design lifetime or maximum usage. An example is flash memorywhich typically can support a number of memory erasure operations (suchas in the range of about 10⁴ through about 10⁵ erasures) but which canbe expected to fail some time after that number of erasures.Accordingly, the expected design lifetime of a flash memory is more afunction of the manner in which it is used (and particularly, itserasure frequency) than the mere passage of time. To achieve a degree ofconfidence in the continued operation of a system which includes flashmemory, the flash memory should be replaced as the number of erasureoperations performed using the flash memory approaches the expecteddesign lifetime of the flash memory. Accordingly, it would be useful toprovide a system in which replacement of the flash memory (or similardata storage medium) will be encouraged, requested, and/or required atan appropriate time.

Although it would be possible to provide a system for manually providinga reminder of the need for a media replacement (such as marking reminderon a calendar) there is a significant risk that this type of reminderwould become unassociated with the data storage medium. For example, ifthe data storage medium is a medium which is a removable medium (movedfrom one computer or other device to another computer or other device, amanual calendar reminder, for example, may not properly reflect theappropriate replacement date for the particular medium which iscurrently inserted in a computer (or other device). Furthermore, amanual reminder such as a calendar entry may be infeasible when designlifetime is based, not on date of installation, but on information thatmay not be readily available for, e.g., manual entry on a calendar, suchas date of manufacture of the medium. Furthermore, when design lifetimeis determined or affected by factors other than mere passage of time(such as number of erasures or similar usage factors) tracking such usedependent factors can be burdensome or infeasible for a manual remindersystem. Accordingly, it would be useful to provide a system in whichaccurate and current design lifetime information, based on appropriatecriteria, remain coupled, preferably physically coupled, to the memorymedium or device.

Although, in a number of computing contexts, it may be possible toconfigure a computer to provide, or assist in providing, appropriatemedia replacement reminders, it can be disadvantageous to imposeadditional computing burden or “overhead” on a CPU (Central ProcessingUnit) for tracking usage of each storage medium and it can be burdensometo impose a programming or data entry burden on programmers or users.Accordingly, it would be useful to provide a system for encouraging orassuring appropriate storage medium replacement without substantiallyincurring or increasing computing, programming or data entry burden.

The type of response which is most appropriate, as theend-of-design-lifetime approaches, will vary depending on such factorsas the type of medium involved and type of computing system or computingnetwork where the device is employed and/or user preferences. Inespecially critical computing environments, it may be undesirable togive a user an opportunity to ignore or override a warning or requestthat media replacement is due. Accordingly, it would be useful toprovide a system in which the system can be configured so as to respondin different fashions to the detection of an approachingend-of-design-lifetime event.

SUMMARY OF THE INVENTION

The present invention provides for storing, and, as appropriate,updating or incrementing system or component information, such asremaining-expected-lifetime information, (or information from whichremaining-expected-lifetime information can be determined or derived)(REL), in a fashion which remains associated with a data storage medium,and, in response, providing an appropriate output, warning or action. Invarious embodiments, the REL information may be stored using the samestorage medium that is used for storing the data for which the datastorage unit is intended (“main storage medium”), e.g., in the headerportion or other portion of the memory array of a flash memory,nonvolatile random access memory (RAM) or other RAM, a header portion ofdisk storage in a fixed or hard disk drive (HDD) and the like.Alternatively, the REL information can be stored on a separate storagedevice such as providing an HDD storage unit with a small flash memoryor other memory mounted on or otherwise coupled to the HDD unit. Ineither case, the memory device (or a portion of memory medium) used forstoring at least a portion of the REL information is physically mountedon or otherwise physically coupled to the data storage unit to which theREL relates. In this context, a data storage unit to which the RELinformation relates is the unit which would normally be replaced at theend of the expected lifetime indicated by the REL information. Forexample, in the case of a flash memory device, the entire flash memorydevice would normally be replaced at the end of the expected lifetime ofthe flash memory. In contrast, a removable medium hard disk drive(RMHDD) may have an expected lifetime for the removable medium which isdifferent from the expected lifetime of the drive mechanism. In thissituation, if REL information relating to the removable medium isprovided, preferably at least some of such REL information is stored ina device which stays with the removable medium when the medium isremoved from the drive (e.g., so that even if the removable medium isinserted in a different drive, it is still possible to detect theappropriate remaining-expected-lifetime and to take the appropriateaction. If REL information is provided in connection with the drivedevice for the RMHDD, it would generally be preferred to store at leasta portion of the REL information related to the drive portion on thedrive itself, (as opposed to on the removable medium) so that even ifnew removable media were inserted in the RMHDD, the appropriate RELinformation related to the RMHDD drive portion would be available.Furthermore, in this situation, if the drive portion of the RMHDD wasreplaced at the end of the expected lifetime of the drive portion, thereplacement RMHDD would preferably contain REL information related tothe replacement RMHDD. In this way the REL information is stored in afashion such that the REL information moves with the data storage unitto which it relates, regardless of replacement of parts or media in theoverall system.

The REL information can be used in a number of fashions. In oneconfiguration, the CPU or similar central computing device canperiodically read the REL information (in a “polling” fashion).Alternatively, the data storage unit can include logic whichperiodically or continuously monitors the REL information and sends aninterrupt signal to the CPU when the remaining expected lifetimeapproaches (is within a relatively small distance from) an indication ofzero remaining lifetime. The REL information stored on the data storageunit may be sufficient, in itself, to determine remaining expectedlifetime (such as a counter in a flash memory holding the remainingexpected available erasures) or may be information which is combinedwith information stored elsewhere in order to calculate, look up orotherwise determine remaining expected lifetime (such as a serial numberor other identifier number stored in the data storage unit which is usedto index into a data base of REL information stored elsewhere. In anycase, once it is determined that the data storage unit is approachingthe end of its expected life time, the information which is output(either in a polling fashion or an interrupt fashion) can be used totrigger one or more of a plurality of responses. In one embodiment, aCPU can be receive such an output and provide a display, printout, alarmor similar output (such as by a monitor, or other screen, printer,speaker and/or sound card and the like) to alert a user or administratorthat the device needs replacing, maintenance attention and the like.Although its possible to provide the entire system (detection and outputof warning) in the context of a single computer such as a personalcomputer (PC), work station or similar computer, it is also possible toprovide the warning at a remote location such as a system administratoror technical support location, a computer or computer componentmanufacturer or vendor location and the like. It is also possible toconfigure the system to take different types of actions as the datastorage unit gets closer and closer to the end of expected lifetime,such as first providing warnings to the user, then providing warnings toa system administrator and finally, preventing any further use,preventing any further writes, preventing further power-ups or similaraction with regard to the storage unit, e.g. until replacement ormaintenance has been performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a computing system with a data storage unitwhich can store remaining expected lifetime information according to anembodiment of present invention;

FIG. 2 is a block diagram of a flash memory device according to anembodiment of the present invention;

FIG. 3 is a flow chart of a procedure for providing and using remainingexpected lifetime information according to an embodiment of the presentinvention;

FIG. 4 is a block diagram of a non-volatile RAM device according to theembodiment of the present inventions;

FIG. 5 is a schematic block diagram of a hard disk drive according to anembodiment of the present invention; and

FIG. 6 is a block diagram of a removable medium hard disk driveaccording to a embodiment of the present invention.

DETAILED DESCRIPTION

As depicted in FIG. 1, a data storage unit 112 is commonly coupled to,or part of, a larger system 114 which may include, for example, othercomponents of a computer (such as a personal computer, work station,laptop or palmtop computer, or telecommunications device such asrouters, bridges and the like) 116 and, in some configurations, othercomputers or similar devices 118 a, b, c, e.g. coupled by a local areanetwork (LAN) 122, wide area network (WAN), Internet link 124, or byserial or dedicated point-to-point connections, and the like, or can becoupled to non-computer devices, such as televisions, stereo equipment,microwave ovens, and the like. As depicted in FIG. 1, the computer 116includes the data storage unit 112 and typically contains componentssuch as a CPU 126, CRT or LCD screen 128 or other video monitor, printer132, audio speaker 134 and other components, as is well known in theart. The data storage unit 112, in the embodiment of FIG. 1, includes anormal or main memory area 114 for storing the data for which the datastorage unit 112 is intended. For example, when the data storage unit isa flash memory, random access memory or the like, the normal memory 114is an array of memory cells, and when the data storage unit 112 is adisk drive, the normal memory area 114 is one or more magnetic storagedisks. Many types of normal memory 114 contain a portion 138 dedicatedto storing system information (often in the extreme beginning or endregions of the normal memory 112) and often termed a “header” region. Insome configurations the data storage unit 112 is self-contained in thesense that the data storage unit 112 is not normally removed from thecomputer 116, other than for replacement in case of failure or at theend of its design lifetime. In other situations, a data storage unit 112may be configured to be normally removable from the computer, such as adisk unit which is removable in the context of a removable media harddisk drive. Although the embodiment of FIG. 1 shows the computer 116with one data storage unit 112, computers may be provided with aplurality of data storage units and, in different configurations, none,some or all of the data storage units may be removable. When thecomputer 116 has more than one data storage unit, it is possible to usefeatures of the present invention in connection with only one, some, orall of the data storage units in the computer.

In various embodiments of the present invention,remaining-expected-lifetime (REL) information is stored in a fashionthat is physically coupled to the data storage unit such as by beingstored in the normal memory 114 or in a separate storage device 142which is physically coupled to the data storage unit 112. When aseparate storage device is provided, a number of data storage devicescan be used for this purpose including a separate flash memory,register, hardware counter, DRAM (dynamic random access memory), SRAM(static random access memory), EEPROMS (electronically erasableprogrammable read only memories), PAL (programmable array logic), or PGA(programmable gate arrays). It is possible to store REL information bothin normal memory 114 and in a separate storage device 142, either induplicate form or in such fashion that the REL information in normalmemory 114 is different from at least some REL information stored in aseparate storage device 142. When the REL information is stored in thenormal memory 114, it may be stored in a header or other system area138, in the non-header area 144 or in both areas (either in duplicate ordistributive fashion). When a separate storage device 142 is provided,it may be used for storing only REL information or may be used forstoring other information as well. As one example, anon-removable-medium hard disk drive may be provided with a small flashmemory 142, mounted in the hard disk drive chassis (142) and theseparate memory storage device 142 can be used to store, in addition toREL information (or in place of REL information) information which isused for operating or accessing data stored on the disk, such asso-called “super block” information, file access table (FAT) informationand the like, in duplicate, exclusive or distributed fashion.Preferably, in such embodiment, information stored in the separatestorage device 142 can be used to recover or access information storedin normal memory 114, even after a head crash or similar problem hasdestroyed an on-disk super-block, FAT or similar information.

A number of types of information can constitute, or form part of, RELinformation. The type of information that will be stored as RELinformation depends on factors such as the type and configuration of thestorage medium (since flash memory lifetime may be based on number oferasures while nonvolatile memory lifetime may be based on e.g. batteryusage), the procedures used for detecting impending end of design life(incrementation of a counter may be desired when the data storage unitcontains within itself a direct indication of remaining lifetime whileincrementation of REL data may be unnecessary if the REL data is, e.g.,a serial number for indexing to a remote database) and the like.Preferably, REL information access procedures and formats are at leastpartially standardized so that computers or computing systems can makeeffective use of the REL information regardless of differingmanufacturers, vendors, and the like. In one embodiment, two or moredifferent standards are available and the data storage unit can outputinformation indicating which standard is being used.

Although it is possible to use REL information stored on the datastorage unit which, once stored, is not, thereafter, changed (such as aserial number), preferably, REL information stored on the data storageunit includes at least some information which is written or modifiedduring the course of normal use of the data storage unit (such as ahardware or software counter which is decremented or incremented inresponse to usage events such as flash memory erasure and the like).

Reading some or all of the REL information or writing REL informationcan be performed using read/write logic which is located on (or coupledto) the data storage unit 146 or can be performed using logic which islocated elsewhere, including performing reads or writes under directcontrol of the CPU 126. Providing separate read/write logic 146 (whetherphysically coupled to the data storage unit or located elsewhere) can beuseful in avoiding imposing any additional computing or programmingburden with respect to the CPU 126.

In one embodiment, the logic 146 which achieves reading and/or writingthe REL information is substantially transparent in the sense that allor substantially all signals, interfaces, protocols and the like foroperating the data storage unit will be identical for a data storageunit 112 which includes REL information storage according to the presentinvention compared to a data storage unit without this feature, such asa previously available data storage unit. For example, in oneembodiment, the CPU 126 provides the same data, address and controlsignals to the data storage unit 112 of the present invention as wouldhave been provided for a prior art data storage unit but the datastorage unit 112 contains (or is physically or logically coupled to)logic circuitry which achieves the necessary reading or writing of RELinformation and outputs an interrupt to the CPU 126 when the remainingexpected lifetime of the data storage unit 112 is approaching zero. Inthis configuration, the only modification to the computer 116 or system114 needed for utilizing the REL information would be to provideprocedures for responding to such an interrupt signal. For example, inone embodiment, the CPU 126 may be controlled by programs which providethat, in response to such an interrupt, the CPU 126 will control thescreen 128, printer 132 and/or audio output 134 to provide a warning oralarm.

Such warnings can take a plurality of forms such as identifying thepertinent component and informing the user that the end of the expectedcomponent lifetime is approaching, providing an estimated remaininglifetime, preferably in chronologic form, instructing the user how toobtain replacement, instructing or suggesting to the user that databackup procedures should be performed, automatically performing databackup procedures, disabling further use of the component and the like.

When the system 114 includes other computers 118 a, b, c or similarcomponents, the CPU 126 may be configured to, output a message over anetwork, such as local network 122, wide area network or Internetconnection 124. For example, information about an impendingend-of-design-lifetime event can be automatically forwarded to a systemadministrator computer 118 a or a technical support computer 118 a sothat the appropriate personnel can be notified that a identifiedcomponent in an identified computer needs to be replaced or otherwiseserviced. In one embodiment, in response to detection of anend-of-design-lifetime event, programming will control the CPU 126 tooutput a message to a manufacturer or vendor 118 c, which may be themanufacturer or vendor which made or sold the about-to-expire datastorage unit, and which can respond in any of a number of fashions,including sending an e-mail or other notice to the user about theimpending end-of-design-lifetime event, provide a price quotation oroffer for a replacement (or upgrade) device and/or installation,automatically (e.g. in accordance with a previous arrangement) ship areplacement unit or and/or schedule a replacement unit installation,preferably automatically billing or charging an appropriate account.

FIG. 2 depicts a flash memory that may be used in accordance with oneembodiment of the present invention. In the embodiment of FIG. 2, aflash memory 212 is coupled, in a computer system, using a plurality ofdata lines or buses including, e.g. one or more power lines address line216 b and interrupt line 216 c data lines 216 d read/write or othercontrol lines 216 e and flash memory erase control line 216 f. The flashmemory 212 includes a normal or main memory area 218 comprising aplurality of memory cells, and having at least one header area 222.Memory control (read/write) circuitry 224 in response to, e.g., dataaddress and control signals, performs memory operations such as memoryreads, writes, and erase operations in a manner known to those of skillin the art. In the embodiment depicted in FIG. 2, REL logic (RELinformation read/write) circuitry 226 is provided on the flash memory212. Although the REL logic 226 is depicted as being spaced from theflash memory read/write logic 224, it is possible to provide the logiccircuitry for read/write and the logic circuitry for REL functions inthe same area. One advantage of providing the REL logic, on the datastorage unit is the assurance that counters and similar information willbe properly updated (incremented, decremented and the like) regardlessof what type of machine the flash memory is used in, i.e., the flashmemory depicted in FIG. 2 is not restricted to use only in machines orcomputers that have been programmed to perform updates of the RELinformation.

As depicted in FIG. 3, in one embodiment, a counter 232 in a header area222 has stored in it an initial value indicative of the maximum numberof permissible erasures for the flash memory 212. In the depictedembodiment, the maximum is stored 312 during manufacture of the flashmemory 314. However, it is possible to provide embodiments in which RELinformation is initialized at other times, such as during installationor configuration 316 of the flash memory. In some situations it may bepreferable to provide for storing or initializing at least some RELinformation other than by the manufacturer, such as when a systemadministrator may wish to provide for a relatively large number oferasures for a majority of flash memories in a system but to provide fora relatively lower number of permissible erasures in certain devices (inorder to provide for a higher level or confidence in the reliability ofsuch devices e.g. for mission-critical uses). Other types of informationmay be provided as initial REL information, either in addition to or inplace of a maximum number of permissible erasures, either duringmanufacturer 314 or installation/configuration 316, including storing aserial number or similar identifier 318 storing a date of manufacture320 storing a universal resource locator (URL) 324 (e.g. for embodimentsin which approaching expected end of lifetime triggers the sending of amessage to a remote site 118 a, 118 b, 118 c) and/or storing a date ofinstallation or configuration 326.

In the depicted embodiment, a number of comparisons or tests against thevalue of the counter are performed during boot-up 328 of the computer orsystem in which the flash memory is located. In other embodiments,rather than performing the comparisons only during each boot-up, thecomparisons can be performed in other fashions such as periodically(once a day, once an hour, etc.) and preferably in a fashion which isconfigurable by a user, system administrator and the like. Preferablythe comparisons or tests are performed by logic circuitry which ispositioned on the flash memory 226. Those of skill in the art willunderstand, after reading the present disclosure, how to design andprovide logic circuitry which performs the tests and other functionsdepicted in FIG. 3 and described generally herein.

In the embodiment depicted in FIG. 3, a comparison is performed todetermine whether the value currently in the counter is less than awarning threshold. The warning threshold may be a value which is storedor hardwired by the manufacturer or may be a value which can be stored,set or modified by the user or system administrator.

As the value of the header counter is decremented and approaches a zerovalue, when the value falls below the warning threshold 332, the RELlogic 226 will cause the flash memory to output an interrupt 216 c towhich the computer 126 responds by outputting a warning 334 or takingother appropriate action, examples of which are provided herein.

The value to be used for the warning threshold will depend upon a numberof factors such as the expected frequency of flash memory erasures andthe expected frequency with which the comparison 322 will be performed.For example, if it is expected that about 50 flash memory erasures mayoccur per day and if boot-up 28 is expected to occur once per day,preferably the warning threshold would be greater than 50 so that, onaverage, a user would receive a warning at least one day before theexpected-end-of-lifetime event for the flash memory.

As depicted in FIG. 3, it is possible to provide for other tests orcomparisons (in addition to or in place of the tests relating to themaximum number of permissible erasures) such as testing whether the ageof the flash memory, since its manufacturer, exceeds a first agethreshold 336. It is also possible to, e.g., determine whether the ageof the flash memory since its installation exceeds second age threshold338. As described generally above, it is also possible to provideembodiments in which a disablement threshold is provided, such that, ifthe header counter exceeds a disablement threshold 340 (which may be,e.g., zero) the data storage unit is disabled 342, such as by causingthe CPU to refuse to provide any control signals to the flash memory212.

After the boot-up 328 and preferably regardless of the outcome of theboot-up tests 332, 336, 338, 340, certain operations of the flash memory212 are monitored during use 344. For example, in the depictedembodiment, in which the header counter is intended to maintain anindication of the number of permissible erasures remaining, the RELlogic 226 will monitor 234 erase signals or commands 216 f, preferablylooping continuously 346 until an erasure operation is detected 348, inwhich case the header counter 232 will be decremented 352 before loopingback 346 to continue monitoring. In this fashion, every time there is anerasure operation, the header counter will be decremented and thus theheader counter will retain the maximum number of permissible erasuresremaining for the flash memory 212.

FIG. 4 depicts an embodiment in which REL information is stored on anonvolatile NVRAM 412. In the depicted embodiment, the nonvolatile RAMincludes a main memory area 418 row and column address decoders, senseamps and the like 419 a 419 b. Read/write and control logic 424 and oneor more batteries 438, typically a lithium battery, to power the refreshcycles needed to maintain contents of main memory 418 when the NVRAM isnot receiving power 414. For purposes of illustration, in aconfiguration in which the battery 438 can be expected to have alifetime related to the number of charge/discharge cycles, the NVRAMwill be provided with REL logic 426 which includes a counter which isinitialized to the maximum number of expected charge/discharge cycles.The REL logic 426 can be configured to monitor occurrences ofcharge/discharge cycles e.g. by monitoring the battery charge line 442,a discharge or battery supply line 446, and/or monitoring 448 the powerline 414. In use, the REL logic 426 will decrement the charge/dischargecounter during each discharge cycle and, when the counter falls below awarning threshold, will output an interrupt signal which can be used ina number of fashions, such as outputting a warning to the user,contacting a system administrator computer or other remote site and thelike. Preferably, the counter can be reset to a maximum number ofexpected charge/discharge cycles when the battery is replaced.

Although, as described above, it is desired to store at least some ofthe REL information in a fashion which moves with the data storage unit,it is possible to store some or all of the REL information in a storagedevice different from the main storage media of the data storage unit.For example, as illustrated in FIG. 5, where the data storage unit is adisk drive 512, although it is possible to store some or all RELinformation on the disks 518 a, b, c, the embodiment of FIG. 5 providesfor non-volatile memory (NVROM) such as flash memory 552 orbattery-backed-up memory, coupled to REL control logic 526, for storingREL information. If desired, the disks 518 a, b, c can be used to storeREL information relating to the NVROM (such as remainingcharge/discharge cycles). In this way a medium or device other than thatwhich is being protected by the storage of REL information is used tostore the REL information. The manner of using the embodiment of FIG. 5is generally analogous to that described above for the examples of FIGS.2 and 4. In general, if the expected lifetime of the disk drive 512 isbased on the number of hours in service, the flash memory 552 mayinclude a counter which is initialized to the total number of servicehours expected and the REL logic 526 is configured to decrement thecounter once per hour, during use, and to output an interrupt signalwhen the value of the counter falls below one or more thresholds. Ifdesired, it is possible to use the flash memory 552 to store otherinformation, i.e. information in addition to or in place of any or allREL information, such as storing a copy of FAT tables, super blockinformation, ECC (error correction code) information and the like (induplicate form, in distribution form, or in exclusive form) in the flashmemory 552 such that, in case of a head crash or other failure,information in the flash memory 552 may be used to recover some or allof the data stored on the disk 518 a, b, c.

As noted above, it is generally desired to provide for storage of atleast some REL information in a fashion which moves with the device towhich the REL information pertains. For example, in the embodiment ofFIG. 6, a drive device for a removable medium hard disk drive (RMHDD) isprovided with flash memory or other storage device 625 for storing RELinformation related to the expected lifetime of the drive 612. Thus,even when the removable media packs 654 a 654 b are removed or insertedinto the RMHDD 612, expected lifetime information pertinent to the drive612 is maintained. In one embodiment, the media packs 654 a, b eachcontain their own flash memory or other information storage devices 656a, b for storing REL information pertinent to the removable media packs.

A given piece of hardware thus might have numerous pieces of RELinformation stored. For example, for a given hard drive, there could bestorage of information relating to drive motor lifetime, head wear,battery lifetime, and so forth. When a system administrator or othercentral figure is responsible for taking appropriate actions asend-of-lifetime events approach, it would be useful to provide an optionfor the system administrator to be able to review all REL informationavailable in the system (or selectable portions thereof), substantiallyall at one time or place, such as providing for storage of current,system-wide REL information in a central database (updated continuously,or on demand, in a push or pull manner). Preferably, as new componentsor hardware are added to the system, the system queries to components toidentify the type of REL information that is available on that hardwareor component.

In light of the above description, a number of advantages of the presentinvention can be seen. The present invention permits reliableinformation regarding expected lifetime of a device to be used (e.g. foroutputting warnings or taking actions) even when data storage units aremoved from one computer or other device to another. The presentinvention provides the opportunity for end users, system administrators,technical support personnel and the like to take appropriate action,such as replacing or maintaining components, as components approach theend of their expected lifetimes. The present invention providesmanufacturers, vendors and others the opportunity to offer replacementand/or upgrade components to users at or near the time that users wouldtypically need to perform such upgrades. The present invention appearsto be particularly advantageous in connection with data storage unitswhich have relatively well-defined expected lifetime and/or data storageunits which are not uncommonly removed, replaced or moved from onemachine to another.

A number of variations and modifications of the present invention can beused. It is possible to use some aspects of the invention without usingothers, such as providing for storage of REL information which moveswith a data storage unit without providing for warnings to end users. Insome situations, it may be desirable to configure one or more computers116 with multiple data storage units 112 such that, in response to thedetection of an impending end-of-design-life event for one data storageunit 112, the computer will automatically (i.e. without the need forhuman decision or manipulation) copy data from a data storage unit 112such as a first flash memory which is approaching its design lifetimelimit to another, substantially unused data storage unit (or a datastorage unit with substantial remaining lifetime), such as a secondflash memory preferably in a manner substantially transparent to theuser. Although providing the REL logic 226 on the flash memory 212 isuseful in avoiding imposing additional computing or programming burdenon the CPU and/or programmers, it is possible to configure an operablesystem in which some or all of the REL functions described herein,including some or all of the comparison or test functions, such as thosedepicted in FIG. 3, are implemented using software and/or are performedby the CPU 126. In one embodiment, once a maximum number of writes hasbeen performed, information can be written to a PAL device, e.g. so asto disable further writes (until the PAL is re-programmed). Althoughexamples of items with limited duration or number of uses have beengiven other items can benefit from the present invention, including, forexample, magnetic tapes and tape drives, devices with a limited numberof insertions, backplanes and insertion handles (e.g. having a limitednumber of mating cycles), writable disks, re-writable disks, DVD RAMs,and the like.

The present invention, in various embodiments, includes components,methods, processes, systems and/or apparatus substantially as depictedand described herein, including various embodiments, subcombinations,and subsets thereof. Those of skill in the art will understand how tomake and use the present invention after understanding the presentdisclosure. The present invention, in various embodiments, includesproviding devices and processes in the absence of items not depictedand/or described herein or in various embodiments hereof, including inthe absence of such items as may have been used in previous devices orprocesses, e.g. for improving performance, achieving ease and/orreducing cost of implementation.

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein. Althoughthe description of the invention has included description of one or moreembodiments and certain variations and modifications, other variationsand modifications are within the scope of the invention, e.g. as may bewithin the skill and knowledge of those in the art, after understandingthe present disclosure. It is intended to obtain rights which includealternative embodiments to the extent permitted, including alternate,interchangeable and/or equivalent structures, functions, ranges or stepsto those claimed, whether or not such alternate, interchangeable and/orequivalent structures, functions, ranges or steps are disclosed herein,and without intending to publicly dedicate any patentable subjectmatter.

What is claimed is:
 1. Apparatus for a data storage unit having at leasta main data storage medium for storing data, comprising: an electronicdata storage device, comprising a header portion of said main datastorage medium, which stores at least first remaining-expected-lifetime(REL) information usable for determining remaining expected lifetime ofsaid data storage unit, said electronic data storage device beingphysically coupled to said data storage unit; at least a first outputline for outputting at least a first signal related to theremaining-expected-lifetime of said data storage unit.
 2. Apparatus, asclaimed in claim 1, wherein said data storage unit is selected from thegroup consisting of: flash memory; non-volatile RAM; a tape drive; are-writable disk; a hard disk drive; and a removable media hard diskdrive.
 3. Apparatus, as claimed in claim 1 wherein said electronic datastorage device is separate from said main data storage medium. 4.Apparatus, as claimed in claim 1 wherein said REL information is updatedin response to usage of said data storage unit.
 5. Apparatus, as claimedin claim 4, further comprising logic circuitry, physically coupled tosaid data storage unit, which updates said REL information.
 6. A methodfor use with a data storage unit having at least a main data storagemedium for storing data, comprising: providing an electronic datastorage device different from said main data storage medium, saidelectronic data storage device being physically coupled to said datastorage unit; storing system information in said electronic data storagedevice; outputting said system information from said data storagedevice; wherein said system information includes at least firstremaining-expected-lifetime (REL) information usable for determiningremaining expected lifetime of said data storage unit and wherein saidstep of outputting includes outputting, from said data storage unit, atleast a first signal related to the remaining-expected-lifetime of saiddata storage unit; displaying a warning of impending end of lifetime ofsaid data storage unit, in response to said outputting of said firstsignal.
 7. A method, as claimed in claim 6 further comprising updatingsaid REL information in response to usage of said data storage unit. 8.A method, as claimed in claim 6, further comprising sending, to a remotecomputer, a message indicating impending end of lifetime of said datastorage unit, in response to said outputting of said first signal.
 9. Amethod, as claimed in claim 6, further comprising disabling said datastorage unit in response to said outputting of said first signal.
 10. Amethod, as claimed in claim 6, wherein said data storage unit is a harddisk drive, and further comprising storing superblock informationrelating to said hard disk drive on said electronic data storage device.11. Apparatus for a data storage unit having at least a main datastorage medium for storing data, comprising: electronic means,comprising a header portion of said main data storage medium for storingat least first remaining-expected-lifetime (REL) information usable fordetermining remaining expected lifetime of said data storage unit, saidelectronic means for storing being physically coupled to said datastorage unit; means for outputting at least a first signal related tothe remaining-expected-lifetime of said data storage unit. 12.Apparatus, as claimed in claim 11, wherein said electronic means forstoring comprises a portion of said main data storage medium. 13.Apparatus, as claimed in claim 11 wherein said electronic means forstoring is separate from said main data storage medium.
 14. Apparatus,as claimed in claim 11 further comprising means for updating said RELinformation in response to usage of said data storage unit. 15.Apparatus, as claimed in claim 14, wherein said means for updating isphysically coupled to said data storage unit.
 16. Apparatus as claimedin claim 11, wherein said data storage unit comprises a flash memory,said header region including at least a first counter initialized to afirst value, further comprising: read/write circuitry configured to readand write from and to said main memory; and logic circuitry configuredto monitor erase operations performed on said flash memory and, inresponse, decrement said counter.
 17. Apparatus as claimed in claim 16,wherein said logic circuitry is further configured to output, from saidflash memory, at least a first signal when said counter stores a valuewhich is less than at least a first threshold value.
 18. A non-volatileRAM comprising: a main memory for storing data, said main memoryincluding a header region, said header region including at least a firstcounter initialized to a first value; a battery for providing power forrefresh operations when external power is unavailable; read/writecircuitry configured to read and write from and to said main memory;logic circuitry configured to monitor charges of said battery and, inresponse, incrementing said counter.
 19. A non-volatile RAM, as claimedin claim 18, wherein said logic circuitry is further configured tooutput, from said non-volatile RAM, at least a first signal when saidcounter stores a value which is greater than at least a first thresholdvalue.